Night vision cameras which operate under extremely low light levels are known in the art. Such cameras frequently utilize a microchannel plate or a highly sensitive photocathode for sensing of low light levels. A focused electron bombarded hybrid photomultiplier tube comprising a photocathode, focusing electrodes and a collection anode disposed in a detector body is disclosed in U.S. Pat. No. 5,374,826 issued Dec. 20, 1994 to LaRue et al and U.S. Pat. No. 5,475,227 issued Dec. 12, 1995 to LaRue. The disclosed hybrid photomultiplier tubes are highly sensitive but do not sense images. A surveillance system having a microchannel image intensifier tube is disclosed in U.S. Pat. No. 5,373,320 issued Dec. 13, 1994 to Johnson et al. A camera attachment converts a standard daylight video camera into a day/night vision video camera.
Image sensing devices which incorporate an array of image sensing pixels are commonly used in electronic cameras. Each pixel produces an output signal in response to incident light. The signals are read out, typically one row at a time, to form an image. Image sensors which incorporate an amplifier into each pixel for increased sensitivity are known as active pixel sensors. Active pixel sensors are disclosed, for example in U.S. Pat. No. 5,789,774 issued Aug. 4, 1998 to Merrill; U.S. Pat. No. 5,631,704 issued May 20, 1997 to Dickinson et al; U.S. Pat. No. 5,521,639 issued May 28, 1996 to Tomura et al; U.S. Pat. No. 5,721,425 issued Feb. 24, 1998 to Merrill; U.S. Pat. No. 5,625,210 issued Apr. 29, 1997 to Lee et al; U.S. Pat. No. 5,614,744 issued Mar. 25, 1997 to Merrill; and U.S. Pat. No. 5,739,562 issued Apr. 14, 1998 to Ackland et al.
In general, it is desirable to provide cameras which generate high quality images and which operate over an extremely large dynamic range, including both daytime and nighttime conditions. In addition, the camera should have a small physical size and low electrical power requirements, thereby making head-mounted and battery-operated applications practical.